Small form factor memory card has a large amount of storage space and has erasable memory as storage medium. The Small form factor memory card is built in with a controller for controlling chipset therein and reading and writing data. In application, the Small form factor memory card is connected to an electronic application device compatible with the Small form factor memory card.
The Small form factor memory card has the advantages of small volume, light weight, high speed, power saving, etc., and thus are widely used in computer periphery device and other electronic applications for data storage and exchange. The current used Small form factor memory card includes CompactFlash cards (CF cards), SmartMedia cards (SM cards), MultiMedia cards (MMC cards), MemoryStick cards (MS cards), Secure Digital cards (SD cards), etc. These cards have different sizes, appearances, mechanical structures, electronic contacts, communication protocols, software instructions, control processes, etc.
The Small form factor memory card are widely used in portable digital devices, such as mobile phones, digital cameras, MP3s, PDAs, etc. Other than being used in memory card, they are used in such as modem cards of CF interface, network cards, digital camera cards with memorystick interface, BlueTooth communication cards, etc. To identify with memory cards, above mentioned cards are called as IO cards.
Above mentioned Small form factor memory cards have some disadvantages which will be described in the followings.
For CompactFlash cards, there are 50 joints are necessary in the interface. The electric interface has 8 bits and 16 bits which are used in parallel. The CompactFlash has an address but 26 signals and a variety of control signal wires for different uses.
The defect of CompactFlash is that too many joints are used so that cost is high and a larger space is necessary; a larger force is needed for insertion and withdrawing the cards; the positioning of the pins are not accurate so that the slot is easily damaged; a parallel design must provide selection signals if a plurality of cards are used and thus it is not suitable to be connected with a plurality of cards; no write protection is provided and thus it can not assure that the contents of the memory is correct.
The SmartMedia cards need 22 joints. Reeds and plane contact terminals are used. Two reeds are necessary for detecting whether a memory card is inserted and write protection piece is adhered.
The detect of the SmartMedia is that too many joints and write protection piece induce a larger space is necessary and thus cost is high; the terminals are arranged as two banks. In insertion or withdrawing, the contacts in the first bank will be connected to the contracts in the second banks, thereby, the insertion is unstable; the power signal VCC and ground pin GND are arranged between the two connecting terminals, it is possible that the terminal is short or unstable; the write protection of the memory card is identified by adhering a tap, and thus special conduction write protection tap must be provided; the physical addressing is used and thus linear logic used in the general system can not be supported directly so that the cost of the electronic application device is increased; the expansion of the storage medium causes that the format must be modified to suit the format of the shipset due to the physical addressing.
For MMC card, the interface has seven joints. Reeds and plane contact terminals are used. A further reed is used to detect the insertion of a memory card.
The defect of MMC card is that the serial communication transfer mode is used, and thus only one bit is used in each clock. Thereby, the transmission rate is low; the write protection must be used with special software.
For SD cards, the interface needs 9 joints, reeds and plane contact terminals are used. Moreover, two reeds are used to detect whether a memory card is inserted and detect the sliding block of writing protection.
The defect of SD interface card is that the sliding block must be detected by an electronic application device.
For MS card, the interface of MS card has ten joints, and reeds and plane contact terminals are used. The connecting interface has card inserting detection signals. The memory card has a write protection switch. The advantage of the memory card is that it can support the write protection function.
The defect of the MS interface card is that the serial communication transfer mode is used, and thus only one bit is used in each clock; the physical addressing is used and thus linear logic used in the general system can not be supported directly so that the cost of the electronic application device is increased; the expansion of the storage medium cause that the format must be modified to suit the format of the shipset due to the physical addressing.
Since above mentioned prior art Small form factor memory cards have defects as described above, and personal computers must expand with USB interface, PCMCIA interface, or IDE interface, etc., for communicating with these interface cards. Thereby, the operation is inconvenient and the cost is high.